\begin{tikzpicture}
    \tkzDefPoints{0/0/A, 4/0/B, 1.2/1.2/C}
    \tkzDefLine[parallel=through B, normed](C,A) \tkzGetPoint{D}
    \tkzInterLL(A,B)(C,D)  \tkzGetPoint{O}

    \tkzDrawSegments(A,B  C,D  A,C  B,D)
    \tkzLabelPoints[below](A,D,O)
    \tkzLabelPoints[above](B,C)
\end{tikzpicture}

